The present disclosure relates generally to an arrangement for, and a method of, illuminating and electro-optically reading a target by image capture, and, more particularly, to interchangeable illumination modules that are replaceably mounted on an imaging reader.
Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, in many industries, such as retail, manufacturing, warehousing, distribution, postal, transportation, logistics, etc., to image various targets, such as one- and two-dimensional bar code symbols to be electro-optically decoded and read by image capture, and direct part marking (DPM) targets, e.g., machine-readable, high-density, one- or two-dimensional, optical codes, each DPM code being comprised of multiple elements that are directly marked (imprinted, etched, molded, or dot-peened) on a metal, plastic, leather, or glass, etc., workpiece. A known imaging reader included a scan module or engine mounted in a housing. The scan module included a solid-state imager, e.g., a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, having a sensor array of photocells or light sensors that correspond to image elements or pixels over a field of view of the imager, and associated circuits for producing and processing electrical signals that are processed by a programmed microprocessor or controller into data indicative of the target being decoded and read. The scan module also included an illuminating light assembly for illuminating the target, and an imaging lens assembly for capturing return light scattered and/or reflected from the illuminated target, and for projecting the captured return light onto the sensor array to capture an image of the illuminated target.
Although generally satisfactory for its intended purpose, the known illuminating light assembly emitted illuminating light having fixed optical characteristics, e.g., a predetermined color (wavelength), a predetermined brightness (intensity), a predetermined illuminating light pattern distribution (directionality), a predetermined illumination angle (wide or narrow illumination field), a predetermined property (diffused or non-diffused light), etc. Such optical characteristics, however, were not ideal for different targets in all intended applications. For example, if the target was a bar code symbol that was colored black and printed on a background that was colored green, then an illuminating light that was colored red would be absorbed by both the black and green colors, thereby providing poor contrast between the symbol and the background, and resulting in a sluggish, poor reading performance for the reader. As another example, a typical DPM target was better read with diffused light, rather than non-diffused, specular light. Changing the optical characteristics was not considered practical due to the tight integration between the illuminating light assembly and the other assemblies in the scan module.
Accordingly, it would be desirable to change the optical characteristics of the illuminating light assembly in a simple, easy and rapid manner so that different targets in many different intended applications can be read with an improved reading performance.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and locations of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The arrangement and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.